An update to my previous post. I was able to improive the average lag by disabling the serial monitor, passing a reference of the controller to the polling logic (eliminating the need to loop over the current state and previous state to determine if buttons should be pressed), and adding a 1ms delay between loops (should have realized that the board need some down time between calls). I’ve added the code since I think 8ms is a perfectly good lag result for a diy project.
Have you explored changing the polling logic to interrupt?
Can you provide an example? I only experimented with delay and found that 1 millisecond gave the best improvement.
I’m not familiar with the hardware at hand, but an example is how the PS/2 port on a computer is interrupt based. Where you press a button and it informs the cpu of the button press. I was curious if the hardware you’re working with has something akin to that.
The SNES uses shift registers on the controller. Polling it requires reading the registers to get the current state.